Tensile test specimen chuck



Feb. 12, 1946:' H. Q MANN 2,394,555

' TEN'SILE TEST sPEcIMEN CHUCK f Filed Jan. 29; 1944 6' ll\ I l 1 l HARDLD C MANN,

Patented Feb. 12, 1946 UNITED STATES PATENT OFFICE 2,394,555 rENsILE Tris'r sPEoIMEN CHUCK Harold C. Mann, Arlington, Mass. Application January 29, 1944, serial No. 520,169

(Granted under the act of March 3, 1883, as

amended April 30,1928; 370 0. G. 757) 4 Claims.

The invention described herein may be manufacturedl and used by or for the Government for governmental purposes without the payment4 to me of any royalty thereon.

This invention relates to an improved ch'uck particularly adapted for holding tensile test specimens While being subjected to the stresses incident to the tensile test.

When using conventional round, machined tensile test specimens with threaded ends, considerable expense is incurred and time lost in threading the ends of the specimens. In' addition th'e time consumed in screwing the specimens in and out of the holders may amount to an appreciable part of the time necessary for making a test. The time necessary for threading the Specimens may in some cases amount to more than one-half of the total time necessary to prepare a specimen, and consequently delay completion of the tensile test by just that much.

In adapting a retractable multi-sector jaw type of chuck to the purposes of large production testing on a tensile testing machine, certain improvements were found to be of advantage inV greatly increasing the speed and ease of `receiving and releasing specimens. A pair of chucks embodying the improvements of this invention, when put into use resulted in a. saving of 60% of the time formerly needed for set up and removal of the test specimen. In addition, an improved axial alignment in testing was realized with a resultant improvement in uniformity from the start of initial loading, on autographicallyV recorded curves, together with' less divergence than is usually the case with conventional thread-end specimens.

Accordingly, it is the purpose of this invention to provide an improved type of holder which does not require a threaded specimen and accomplishes savings in both cost and time.

The specific nature of this invention as well as other objects and advantages thereof will clearly appear from a, description of a preferred embodiment as shown in the accompanying drawing in which:

Fig. 1 is a longitudinal sectional'view of the specimenchuck showing the jaws in the closed position.

Fig. 2 is a view similar to Fig. l showing th'e jaws in the open position.

Fig. 3 is a cross sectional view taken along the plane 3-3 of Fig. 2.

In Fig. 1 there is shown in assembled relationship in longitudinal section a chuck or specimen holder embodying this invention.

The chuck consists of a tri-sected jaw assembly E, assembled Aina housing B together with the necessary manipulative parts, such as spring C, thrust washer D, sliding collarG and locating pins F, all assembled on a stud A which serves as a base for the assembly, va spreader for the jaws, and the means for attaching the chuck t0 the machine.

More specically, stud A in Figs. 1 and 2 has a shank I threaded to fit the machine in which the chuck is to be used, but any other manner of attaching or holding the chuck may be used. Next to the shank is a short section 2 of enlarged diameter vwhich serves as a shoulder in assembly with the housing B,-in which it is fastened by means of the thread 3. The portion 4 to the right of the thread is of much smaller diameter and serves as an arbor for the spring C and the sliding washer D. The front end 5 ofthe stud A is tapered, and serves as a spreader for the jaw assembly -E when it is pushed back.

The housing B has a female thread 6 which screws onto the thread 3 of the stud A'and holds the housing B tightly against the shoulder 2. f Beyond the thread 6 is a hollow cylindrical portion 'l in which' the spring C and the thrust Washer D are assembled. l

The spring C is assembled undercompression between the shoulder formed at the juncture of portions 3 and 4 of stud A and the thrust Washer D, exerting suicient pressure against the washer D so that it in turn holds the jaw assembly E in Vthe extreme forward position as shown in Fig.

1 in which position the three sectors I 5 of the jaw assembly E are closed, being held in the closed position by the tapered inside 8 oi? th'e forward portion of the housing B. The sectors I5 of the jaw assembly E are so shaped as to form a hollow cylindrical space I4 back ofl a smaller opening I3 and conical throat I2 when assembled ,in the closed position.

Each sector I 5 of the jaw assembly E is drilled and tapped for a screw F. Each' screw extends up thru a respective slot 9 in the housing B and into the corresponding hole l0 in the collar G. The slots 9 are located so that they are in alignment with the screws F in the jaw sectors E and permit reciprocating movement of the jaw sectors E within the limits of the closed'position shown in Fig. 1 and the open position in which the cylindrical portion II of the jaw sectors is in contact with the cylindrical inner surface 'I of the housing B. In this position the thrust washer D is forced back toward the shoulder of the stud A, resulting in maximum compression of the jaws E are closed to insure satisfactory manipulation of the jaw assembly E by means of the collar G.

The tensile test specimen (not shown)V is fab-V ricated with the ends corresponding to the space within the jaw assembly E, i. e., aV cylindrical` shank, tapered toward the middle tocorrespond with the length, size and taper in the jaw assembly E when in the closed position shown in Fig. 1.

Togutilize the chuck. the collar G is` pushed Vto the rear position, this motion being conveyed by means of the screws F thru the slots Sto the turn moved back, but at the VSametime theeonical form of the end of the stud'A acts as a spreader 'and forces the sectors I5 apart Y,so that the opening I3 is now of greater diameter than that of the cylindrical portion I4 of the'jaw assembly `E in the closed position shown in Fig. vl.

In thisA position the shank of the test specimen canbe inserted thru the opening I3 into the space between the jaws E, whereupon the collar vGis released and the spring C causes the thrust washerAD'to push the jaw sectors I5 back to the forward and closed positionrin which positionthe testspecimen is held securely against any tensile stress. To yrelease the specimen, the collar G is againY pushed back thus opening the jaws I5 and the specimen slipped out. Y Y y It is thus seen that the time and expense necessary for threading the specimen are saved and particularly the Ytime for assembling the vtest specimen in the machine and removing it when the test is concluded have been reduced to a negligiblevalue.l i' f l i Numerous other applications of thisV invention such, for example, as holders for the rodsV which have to be changed or moved frequently or as a locking device inthe case of any reciprocating motion-win occur to those skilled in'theart. In

`some of these Yapplications it may be desirable to 'vary some of the mechanical detailsto suit the demands of a different combination of conditions and requirements, but the, adaptation of this inventionwill be suiliciently clear so that its application will berobvious. Y Y

Y I claim: 1

' l. A chuck comprising of the hollow portion of vsaid body defining a first interior conical surface, a multi-sector jaw` assembly slidably mounted within said hollow portion, said jaw assembly having an exterior conical surface arranged'to cooperate with said iir'st interior conical surface-of the body, a plug member .secured to the other end of said body, a conicalrend portion of said plug member projectinginto' said hollow portion of the body, and said jaw assembly having a recess deiiningV a second 4interior conical surface arranged to cooperate with said conical end portion whereby movement V2,394,555 Y Y of said jaw assembly relative to the Vaxis of said body effects a radial movement of the sectors of said jaw assembly with respect to the axis of said body.

2. A chuck comprising a hollow body, oneY end of the hollow portion of said body dening a first interior conical surface, a multi-sector jaw assembly slidably mounted within said hollow portion, said jaw assembly'having an exterior conical surface arranged to cooperate with said first interior conical surface of the body, a plug member secured to the other end of said body, a consectors I 5 of the jaw assembly E which are in a hollowbody, one end ical end portion of said plug member projecting into saidV hollow portion of the body, said jaw assembly having a recess dening a second interior conical surface arranged to cooperate with said conical end portion whereby movement of said jawassembly relative to the axis of said body effects a radialmovement of the sectors of said jawY assembly with respect to the axis of said body, an operating washer surrounding'said body and slidably mounted thereon, and an extension on each sector of said jaw assembly projecting thru respective slots in said body and connected to said operating washer.

3. A chuck comprising VaV hollow cylindrical body, one endrof the hollow portion of said body being interiorly threadedV and the' other end shaped to define a first interior conical surface, a plug member screwedinto the threaded end of said body, a reduced diameter portion of said plug member! projecting into the hollowportion of said body-and terminating in a conical end of equal slope to said first said body, said assembly having an exteriorconical surface arranged to cooperate with said'interior conical Vsurface of the body and a recess dening a second interior conicalv surface arranged to cooperate with said conical end of said plug shaped to denne a first interior conicalsurface, a plug member screwed into the threaded end of said body, areduced diameter portion of said plug member projecting into the hollow portion of said body and terminating in'a ycorneal endof equal slope to said rst interior conical surface, a multi-sector jaw assembly slidably mounted within said body, said assembly having an exterior conical surface arranged to cooperate with said interior conical surfaceY of the body, a recess defining a second interior conical surfacefarranged to cooperate with said conical end of said plug member whereby movementof said jaw assembly relative to the axis of said body eects a radial movement of the sectors of said jaw'assembly with respect tothe axis of said body, an operating ring surrounding said body and ,slidably mounted thereon, and a pin radially mounted on each `sector of said jaw assembly projecting thru respectiveslots in said body and connectedto said operating ring. f

interior conical surface, a mul- Y ti-sector jaw assembly slidably mountedrwithin one end of the hollowportion of saidbody being interiorly threaded and the other end HARQLD C. MANN. Y 

